Following statements are regarding to proteins which involve actin filament assembly. A. To nucleate the assembly of branched actin, Arp2/3 needs to be activated by interacting with a nucleation promoting factor (NPF), in addition to associating with the side of a pre-existing actin filament. B. The NPF WASp is inactive due to an intramolecular interaction that masks the WCA domain. C. Two NPFs each bind an actin subunit at their WH2 domains, and together, they activate the Arp2/3 complex through its interaction with their connector and acidic domains. D. The NPF WASp is activated by a coincidence detection mechanism by which intramolecular interaction in WASp is relieved, allowing the W domain to bind actin and the acidic A domain to activate the Arp2/3 complex. Which of the following statements represents regulation of the Arp2/3 complex by NPF? -triyambak.org